1. Field of the Invention
The invention is based on a high-pressure fuel reservoir for a fuel injection system for internal combustion engines, with a reservoir chamber and at least one connection fitting.
2. Description of the Prior Art
In high-pressure fuel reservoirs of this kind, stress peaks occur in the vicinity of the intersection between the inner wall of the reservoir chamber and the bore that connects the reservoir chamber and connection fitting. This results in the danger of the high-pressure fuel reservoir breaking in this region, particularly because the reservoir chamber is subjected to pulsating compressive strain. Various endeavors are undertaken in order to reduce this breakage risk.
One logical possibility is to increase the wall thickness of the high-pressure fuel reservoir. However, there are limitations placed on the wall thickness of the high-pressure fuel reservoir because thick-walled bodies tend to fracture under high, pulsating compressive strain, primarily in the vicinity of wall openings and sharp-edged cross-sectional changes.
DE-OS 196 40 480 A1 has disclosed a cylindrical high-pressure fuel reservoir in which the longitudinal axis of the bore that connects the reservoir chamber and the connection fitting is a secant of the circular reservoir chamber cross section. This results in a reduction of the stresses in the vicinity of the intersection between the bore and the inner wall of the reservoir so that the loading capacity and service life of the high-pressure fuel reservoir are increased.
The object of the invention is to produce a high-pressure fuel reservoir with increased compression capacity, particularly for pulsating compressive strain.
This object is attained according to the invention by means of a high-pressure fuel reservoir in which the reservoir chamber and the connection fitting are hydraulically connected by means of a number of connecting bores. This has the advantage that with the same a hydraulic diameter, the stress peaks produced by the smaller connecting bores are lower than those produced with a single large diameter bore. This increases the compression capacity and service life of the high-pressure fuel reservoir. In addition, the high-pressure fuel reservoir can be adapted to various conditions of use by changing the number and diameter of the connecting bores while simultaneously optimizing the manufacturing costs. Fundamentally, a large number of small diameter connecting bores results in a high compression capacity of the high-pressure fuel reservoir.
In one embodiment of the invention, the reservoir chamber is cylindrical so that can be simply and inexpensively produced.
Another variant provides a spherical reservoir chamber so that except for the connecting regions with the connecting bores, a uniform stress state prevails in the reservoir.
One embodiment of the invention provides for embodying the geometry of the reservoir chamber arbitrarily so that an optimal adaptation to the prevailing stress states is achieved.
In another embodiment of the invention, the connecting bores feed into a collecting bore of the connection fitting so that the connection fitting can be attached in a known manner to a high-pressure line.
In a further development of the invention, one or a number of connecting bores feed into the reservoir chamber tangentially so that the stress peaks produced by the connecting bores are further reduced.
In another embodiment of the invention , the connecting bores feeding into the reservoir chamber tangentially have a larger diameter than the connecting bores that feed into the reservoir chamber non-tangentially so that the stress peaks produced by the connecting bores are approximately equal and consequently the strength of the material is exploited in the best possible way.
In another embodiment of the invention, a high-pressure fuel reservoir is produced by forging so that the material properties are improved.
Another alternative provides that at least one fastening tab is disposed on the high-pressure fuel reservoir so that the reservoir can be simply and securely installed in the vehicle.
In another embodiment of the invention, the high-pressure fuel reservoir is comprised of a tube with a welded-on connection fitting so that production is simplified.